The serious problems associated with adolescent substance use are of great concern to both parents and policy makers. Improved understanding of adolescent needs for treatment for their substance use related problems as well as comorbid psychiatric disorders, and their patterns of service use for these problems is an important first step in accurately targeting preventive intervention and developing improved services for this population. To date, very little is known about: 1) how and where adolescents receive help for substance use related problems and comorbid psychiatric disorders; 2) whether or not the available services actually meet needs for substance use and mental health treatment in this population; and 3) How socio-demographic and other family and individual factors contribute to adolescent utilization of substance treatment services. The proposed study is intended to make an important contribution toward filling these knowledge gaps. The proposed study is based on secondary analysis of the 2000 National Household Survey on Drug Abuse (NHSDA). In recent years, the NHSDA has obtained detailed information about substance abuse/dependence, utilization of substance use treatment services, mental health status, and use of mental health treatment services. It has also increased its sample size significantly. Therefore, it now provides a unique opportunity to examine adolescent utilization of substance use treatment services in the community. Information obtained from 19,430 adolescents (ages 12-17), who participated in the 2000 National Household Survey on Drug Abuse will be used in this study. The study will: 1) assess adolescent need, use and unmet need for substance use treatment services in the community; examine the association between adolescent substance abuse patterns and their use of substance use treatment services; 2) examine the effects of age, gender, and ethnicity (predisposing characteristics); family income and health insurance status (enabling factors); availability of substance use treatment services in the community; and parental attitudes towards child substance use, on adolescent use of substance treatment services; 3) examine the relationship of adolescent substance abuse/dependence and comorbid mental disorders with substance use treatment and mental health service use; and 4) develop and test a model of adolescent utilization of substance use treatment services based on the theoretical framework of the Behavioral Model of Health Services Use. The findings of the study will provide useful information for clinicians and policy makers, who can use it to improve service delivery for adolescents with substance use problems.